Conventionally, probe pins arranged in an IC socket for use as a socket for electric parts have beer known as this type of electric contacts. This IC socket is disposed on a wiring board and configured to house an IC package which is an inspection object. Terminals of this IC package are electrically connected to electrodes of the wiring board through the probe pins.
The probe pins have a structure in which a foundation layer and a surface layer are formed on a base material. On the other hand, some of the terminals of the IC package are formed from so-called lead-free solder not containing lead and composed primarily of tin. These probe pint and terminals are electrically connected to each other as the result of being brought into contact with each other to conduct a continuity test (see, for example, Patent Literature 1).